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FANUC Series 0i-MODEL F Plus. CONNECTION MANUAL (FUNCTION) - page 380

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APPENDIX

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D. PARAMETER TUNING FOR

ENHANCEMENT OF
MACHINING QUALITY

2 Tuning if there is problem

2-1 Tuning of AI contour control

Tune the parameter according to priority for each purpose (Reducing vibration, Reducing machining error,
Enhancing machining quality, Reducing cycle time).

Tuning priority

Priority High :

◊◊

/ Middle :

◊

/ Low : None

Purpose

Machining

Tuning item (Upper : Parameter number / Lower : Tuning rage)

Acc. rate for

Acc./Dec.

before

interpolation

(No.1660)

Time const.

for bell-type

Acc./Dec.

before

interpolation

(No.1772)

Time const.

for Acc./Dec.

after

interpolation

(No.1769)

Corner feed

rate

difference

(No.1783)

Allowable

acc. rate for

circular

interpolation

(No.1735)

Allowable

acc. rate for

small line

blocks

(No.1737)

Parts

250 to 5000

16 to 64

8 to 48

150 to 1000

200 to 3750

Die-mold

8 to24

Reducing

vibration

Parts

Decrease

◊

Increase

◊

Increase

◊◊

Decrease

◊

Decrease

Die-mold

Increase

Reducing

machining

error

Parts

Decrease

Increase

Decrease

◊◊

Decrease

◊

Decrease

◊

Decrease

Die-mold

Decrease

◊

Enhancing

machining

quality

Parts

Decrease

Increase

◊◊

Decrease

Die-mold

Increase

◊

Decrease

◊◊

Decrease

◊

Reducing

cycle time

Parts

Increase

◊

Decrease

◊◊

Decrease

Increase

◊

Increase

Die-mold

In case that the priority of parameter is same, tune the parameter with high effect
after confirming the effect of each parameter.

2-2 Countermeasure of vibration for lower frequency

Avoidance of machining point vibration (below 50Hz) after Acc./Dec. by Smart machining point control.

Semi-closed system

Full-closed system

Parameter

number

Recommended

value

No.2564#1

No.2638[0.1Hz]

Vibration freq.[Hz]×10

No.2639

Parameter

number

Recommended

value

No.2570#4

No.2571#3

No.2647[0.1Hz]

Vibration freq.[Hz]×10

No.2648

No.2649

2510

APPENDIX

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D. PARAMETER TUNING FOR

ENHANCEMENT OF
MACHINING QUALITY

D.2

SUPPLEMENT

Supplement A. Details of AI contour control

AI contour control is the function to possible high speed and high precision machining with low machine
vibration and low machining error by following four functions.
The following four functions can be easily understood as the comparison to driving a car.

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APPENDIX

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D. PARAMETER TUNING FOR

ENHANCEMENT OF
MACHINING QUALITY

Acc./Dec. before interpolation, Bell-type Acc./Dec. before interpolation,
Acc./Dec. after interpolation

Acc./Dec. before interpolation is function to accelerate or decelerate for command feed-rate before CNC
interpolates machining program command. Acc./Dec. after interpolation is function to accelerate or
decelerate for each axis feed-rate after CNC interpolates.
In Acc./Dec. before interpolation, set acceleration rate (No.1660), and it is possible to produce smooth
feed-rate curve by bell-type Acc./Dec. before interpolation (No.1772).
Acc./Dec. before interpolation achieve Acc./Dec. without machining error because CNC interpolates
smoothed feed-rate curve with Acc./Dec. before interpolation.
It is possible to more smooth feed-rate curve by using Acc./Dec. after interpolation (No.1769), but
Acc./Dec. after interpolation makes machining error because it makes after CNC interpolation.

APPENDIX

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D. PARAMETER TUNING FOR

ENHANCEMENT OF
MACHINING QUALITY

Difference between Acc./Dec. before interpolation and Acc./Dec. after interpolation

Acc./Dec. before interpolation achieve Acc./Dec. without machining error, but feed-rate of each axis is
not continuous in the corner and it might cause machine vibration or shock.
It is possible to smooth the discontinuous feed-rate point by using Acc./Dec. after interpolation that
accelerate or decelerate for each axis feed-rate after CNC interpolates, but the smoothing of feed-rate by
Acc./Dec. after interpolation occurs machining error as described above.
So, both Acc./Dec. before interpolation and Acc./Dec. after interpolation are necessary functions and it is
important to use well-balance.

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D. PARAMETER TUNING FOR

ENHANCEMENT OF
MACHINING QUALITY

Corner feed rate difference

In the corner, tangential feed-rate curve is smooth, but feed-rate change of each axis is large, so it might
cause machine vibration. In this case, machine vibration can be reduced by deceleration with corner
feed-rate difference (No.1783) in the corner.
Deceleration feed-rate is decided so that there is no difference of setting value of corner feed-rate
difference for each axis or more.
Feed-rate difference under the value of setting corner feed-rate difference in the corner can be smooth by
Acc./Dec. after interpolation. And machining error is reduced by reducing feed-rate difference in the
corner.

Feed-rate in the corner is decided by parameter setting value of corner feed-rate difference and corner
angle.
In case of the same parameter setting value of corner feed-rate difference, if corner angle is smaller,
feed-rate difference of each axis is made below parameter setting value by more deceleration in the
corner.
In case of the same corner angle, if parameter setting value of corner feed-rate difference is smaller,
machine vibration and machining error are reduced by more deceleration in the corner.

APPENDIX

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D. PARAMETER TUNING FOR

ENHANCEMENT OF
MACHINING QUALITY

Allowable acceleration rate for curved surface

In the curved surface, tangential feed-rate curve is smooth, but feed-rate change (=acceleration rate) of
each axis is large, so it might cause machine vibration. Corner deceleration is not effective in the curved
surface. Even if the curved surface is composed of small line segment blocks, corner deceleration is not
effective because feed-rate difference between blocks is small.
In this case, machine vibration can be reduced by limiting acceleration rate with allowable acceleration
rate (No.1735, No.1737) in the curved surface.
Moreover, as corner deceleration, machining error caused by Acc./Dec. after interpolation is reduced by
deceleration in the curved surface.
Different allowable acceleration rate value can be set for small line segment blocks (No.1737) and
circular interpolation (No.1735).

Feed-rate in the curved surface is decided by parameter setting value of allowable acceleration and curved
rate.
In case of the same parameter setting value of allowable acceleration, if curved rate is larger, acceleration
rate of each axis is made below parameter setting value by more deceleration in the curved surface.
In case of the same curved rate, if parameter setting value of allowable acceleration is smaller, machine
vibration and machining error are reduced by more deceleration in the curved surface.

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APPENDIX

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D. PARAMETER TUNING FOR

ENHANCEMENT OF
MACHINING QUALITY

Supplement B. Servo tuning for higher response

Tuning for higher servo stiffness and for improvement of machining accuracy.

Tuning of velocity Loop gain and filter

Measure frequency response by SERVO GUIDE and increase velocity loop gain with keeping the
following three conditions.

(1) Open loop gain below -6dB

where phase = -180 deg

(2) Open loop phase above -150 deg

where gain = 0dB

(3) Closed loop gain below +5dB

-180deg

0dB

(1)

(2)

(3)

-150deg

-6dB

5dB

Red

：

Open loop

Blue

：

Closed loop

When vibration occurs, refer to the following table.

Vibration frequency

Method of tuning

Standard parameter range of filter

Lower 200Hz

Decrease velocity loop gain

－

200 to 400Hz

Apply resonance elimination filter

Attenuation bandwidth : 60 to 100Hz
Damping : 0 to 50%

400 to 1000Hz

Apply resonance elimination filter

Attenuation bandwidth : 100 to 200Hz
Damping : 0 to 10%

Upper 1000Hz

Apply resonance elimination filter

Attenuation bandwidth : 300 to 600Hz
Damping : 0 to 10%

Tuning of velocity feed-forward

Setting of feed-forward coefficient calculated by following formula

Parameter

number

Inertia information

No inertia information

No.2069

100 ×

100

No.2145

APPENDIX

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D. PARAMETER TUNING FOR

ENHANCEMENT OF
MACHINING QUALITY

Tuning of Smart Backlash Comp.

Tuning of Smart Backlash Compensation with DBB and SERVO GUIDE
1.

Measure backlash by DBB and measure length of ball screw and estimated load torque by SERVO
GUIDE

Set measured backlash (Backlash is able to be measured by dial gauge etc. instead of DBB.)

Set length of ball screw and change value of estimated load torque when axis reversing

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